block: Move power management code into a new source file

Move the code for runtime power management from blk-core.c into the
new source file blk-pm.c. Move the corresponding declarations from
<linux/blkdev.h> into <linux/blk-pm.h>. For CONFIG_PM=n, leave out
the declarations of the functions that are not used in that mode.
This patch not only reduces the number of #ifdefs in the block layer
core code but also reduces the size of header file <linux/blkdev.h>
and hence should help to reduce the build time of the Linux kernel
if CONFIG_PM is not defined.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/Kconfig

@@ -228,4 +228,7 @@ config BLK_MQ_RDMA
 	depends on BLOCK && INFINIBAND
 	default y
 
+config BLK_PM
+	def_bool BLOCK && PM
+
 source block/Kconfig.iosched

block/Makefile

@@ -37,3 +37,4 @@ obj-$(CONFIG_BLK_WBT)		+= blk-wbt.o
 obj-$(CONFIG_BLK_DEBUG_FS)	+= blk-mq-debugfs.o
 obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o
 obj-$(CONFIG_BLK_SED_OPAL)	+= sed-opal.o
+obj-$(CONFIG_BLK_PM)		+= blk-pm.o

block/blk-core.c

@@ -42,6 +42,7 @@
 #include "blk.h"
 #include "blk-mq.h"
 #include "blk-mq-sched.h"
+#include "blk-pm.h"
 #include "blk-rq-qos.h"
 
 #ifdef CONFIG_DEBUG_FS
@@ -1726,16 +1727,6 @@ void part_round_stats(struct request_queue *q, int cpu, struct hd_struct *part)
 }
 EXPORT_SYMBOL_GPL(part_round_stats);
 
-#ifdef CONFIG_PM
-static void blk_pm_put_request(struct request *rq)
-{
-	if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending)
-		pm_runtime_mark_last_busy(rq->q->dev);
-}
-#else
-static inline void blk_pm_put_request(struct request *rq) {}
-#endif
-
 void __blk_put_request(struct request_queue *q, struct request *req)
 {
 	req_flags_t rq_flags = req->rq_flags;
@@ -3757,191 +3748,6 @@ void blk_finish_plug(struct blk_plug *plug)
 }
 EXPORT_SYMBOL(blk_finish_plug);
 
-#ifdef CONFIG_PM
-/**
- * blk_pm_runtime_init - Block layer runtime PM initialization routine
- * @q: the queue of the device
- * @dev: the device the queue belongs to
- *
- * Description:
- *    Initialize runtime-PM-related fields for @q and start auto suspend for
- *    @dev. Drivers that want to take advantage of request-based runtime PM
- *    should call this function after @dev has been initialized, and its
- *    request queue @q has been allocated, and runtime PM for it can not happen
- *    yet(either due to disabled/forbidden or its usage_count > 0). In most
- *    cases, driver should call this function before any I/O has taken place.
- *
- *    This function takes care of setting up using auto suspend for the device,
- *    the autosuspend delay is set to -1 to make runtime suspend impossible
- *    until an updated value is either set by user or by driver. Drivers do
- *    not need to touch other autosuspend settings.
- *
- *    The block layer runtime PM is request based, so only works for drivers
- *    that use request as their IO unit instead of those directly use bio's.
- */
-void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
-{
-	/* Don't enable runtime PM for blk-mq until it is ready */
-	if (q->mq_ops) {
-		pm_runtime_disable(dev);
-		return;
-	}
-
-	q->dev = dev;
-	q->rpm_status = RPM_ACTIVE;
-	pm_runtime_set_autosuspend_delay(q->dev, -1);
-	pm_runtime_use_autosuspend(q->dev);
-}
-EXPORT_SYMBOL(blk_pm_runtime_init);
-
-/**
- * blk_pre_runtime_suspend - Pre runtime suspend check
- * @q: the queue of the device
- *
- * Description:
- *    This function will check if runtime suspend is allowed for the device
- *    by examining if there are any requests pending in the queue. If there
- *    are requests pending, the device can not be runtime suspended; otherwise,
- *    the queue's status will be updated to SUSPENDING and the driver can
- *    proceed to suspend the device.
- *
- *    For the not allowed case, we mark last busy for the device so that
- *    runtime PM core will try to autosuspend it some time later.
- *
- *    This function should be called near the start of the device's
- *    runtime_suspend callback.
- *
- * Return:
- *    0		- OK to runtime suspend the device
- *    -EBUSY	- Device should not be runtime suspended
- */
-int blk_pre_runtime_suspend(struct request_queue *q)
-{
-	int ret = 0;
-
-	if (!q->dev)
-		return ret;
-
-	spin_lock_irq(q->queue_lock);
-	if (q->nr_pending) {
-		ret = -EBUSY;
-		pm_runtime_mark_last_busy(q->dev);
-	} else {
-		q->rpm_status = RPM_SUSPENDING;
-	}
-	spin_unlock_irq(q->queue_lock);
-	return ret;
-}
-EXPORT_SYMBOL(blk_pre_runtime_suspend);
-
-/**
- * blk_post_runtime_suspend - Post runtime suspend processing
- * @q: the queue of the device
- * @err: return value of the device's runtime_suspend function
- *
- * Description:
- *    Update the queue's runtime status according to the return value of the
- *    device's runtime suspend function and mark last busy for the device so
- *    that PM core will try to auto suspend the device at a later time.
- *
- *    This function should be called near the end of the device's
- *    runtime_suspend callback.
- */
-void blk_post_runtime_suspend(struct request_queue *q, int err)
-{
-	if (!q->dev)
-		return;
-
-	spin_lock_irq(q->queue_lock);
-	if (!err) {
-		q->rpm_status = RPM_SUSPENDED;
-	} else {
-		q->rpm_status = RPM_ACTIVE;
-		pm_runtime_mark_last_busy(q->dev);
-	}
-	spin_unlock_irq(q->queue_lock);
-}
-EXPORT_SYMBOL(blk_post_runtime_suspend);
-
-/**
- * blk_pre_runtime_resume - Pre runtime resume processing
- * @q: the queue of the device
- *
- * Description:
- *    Update the queue's runtime status to RESUMING in preparation for the
- *    runtime resume of the device.
- *
- *    This function should be called near the start of the device's
- *    runtime_resume callback.
- */
-void blk_pre_runtime_resume(struct request_queue *q)
-{
-	if (!q->dev)
-		return;
-
-	spin_lock_irq(q->queue_lock);
-	q->rpm_status = RPM_RESUMING;
-	spin_unlock_irq(q->queue_lock);
-}
-EXPORT_SYMBOL(blk_pre_runtime_resume);
-
-/**
- * blk_post_runtime_resume - Post runtime resume processing
- * @q: the queue of the device
- * @err: return value of the device's runtime_resume function
- *
- * Description:
- *    Update the queue's runtime status according to the return value of the
- *    device's runtime_resume function. If it is successfully resumed, process
- *    the requests that are queued into the device's queue when it is resuming
- *    and then mark last busy and initiate autosuspend for it.
- *
- *    This function should be called near the end of the device's
- *    runtime_resume callback.
- */
-void blk_post_runtime_resume(struct request_queue *q, int err)
-{
-	if (!q->dev)
-		return;
-
-	spin_lock_irq(q->queue_lock);
-	if (!err) {
-		q->rpm_status = RPM_ACTIVE;
-		__blk_run_queue(q);
-		pm_runtime_mark_last_busy(q->dev);
-		pm_request_autosuspend(q->dev);
-	} else {
-		q->rpm_status = RPM_SUSPENDED;
-	}
-	spin_unlock_irq(q->queue_lock);
-}
-EXPORT_SYMBOL(blk_post_runtime_resume);
-
-/**
- * blk_set_runtime_active - Force runtime status of the queue to be active
- * @q: the queue of the device
- *
- * If the device is left runtime suspended during system suspend the resume
- * hook typically resumes the device and corrects runtime status
- * accordingly. However, that does not affect the queue runtime PM status
- * which is still "suspended". This prevents processing requests from the
- * queue.
- *
- * This function can be used in driver's resume hook to correct queue
- * runtime PM status and re-enable peeking requests from the queue. It
- * should be called before first request is added to the queue.
- */
-void blk_set_runtime_active(struct request_queue *q)
-{
-	spin_lock_irq(q->queue_lock);
-	q->rpm_status = RPM_ACTIVE;
-	pm_runtime_mark_last_busy(q->dev);
-	pm_request_autosuspend(q->dev);
-	spin_unlock_irq(q->queue_lock);
-}
-EXPORT_SYMBOL(blk_set_runtime_active);
-#endif
-
 int __init blk_dev_init(void)
 {
 	BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));

block/blk-pm.c

@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/blk-pm.h>
+#include <linux/blkdev.h>
+#include <linux/pm_runtime.h>
+
+/**
+ * blk_pm_runtime_init - Block layer runtime PM initialization routine
+ * @q: the queue of the device
+ * @dev: the device the queue belongs to
+ *
+ * Description:
+ *    Initialize runtime-PM-related fields for @q and start auto suspend for
+ *    @dev. Drivers that want to take advantage of request-based runtime PM
+ *    should call this function after @dev has been initialized, and its
+ *    request queue @q has been allocated, and runtime PM for it can not happen
+ *    yet(either due to disabled/forbidden or its usage_count > 0). In most
+ *    cases, driver should call this function before any I/O has taken place.
+ *
+ *    This function takes care of setting up using auto suspend for the device,
+ *    the autosuspend delay is set to -1 to make runtime suspend impossible
+ *    until an updated value is either set by user or by driver. Drivers do
+ *    not need to touch other autosuspend settings.
+ *
+ *    The block layer runtime PM is request based, so only works for drivers
+ *    that use request as their IO unit instead of those directly use bio's.
+ */
+void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
+{
+	/* Don't enable runtime PM for blk-mq until it is ready */
+	if (q->mq_ops) {
+		pm_runtime_disable(dev);
+		return;
+	}
+
+	q->dev = dev;
+	q->rpm_status = RPM_ACTIVE;
+	pm_runtime_set_autosuspend_delay(q->dev, -1);
+	pm_runtime_use_autosuspend(q->dev);
+}
+EXPORT_SYMBOL(blk_pm_runtime_init);
+
+/**
+ * blk_pre_runtime_suspend - Pre runtime suspend check
+ * @q: the queue of the device
+ *
+ * Description:
+ *    This function will check if runtime suspend is allowed for the device
+ *    by examining if there are any requests pending in the queue. If there
+ *    are requests pending, the device can not be runtime suspended; otherwise,
+ *    the queue's status will be updated to SUSPENDING and the driver can
+ *    proceed to suspend the device.
+ *
+ *    For the not allowed case, we mark last busy for the device so that
+ *    runtime PM core will try to autosuspend it some time later.
+ *
+ *    This function should be called near the start of the device's
+ *    runtime_suspend callback.
+ *
+ * Return:
+ *    0		- OK to runtime suspend the device
+ *    -EBUSY	- Device should not be runtime suspended
+ */
+int blk_pre_runtime_suspend(struct request_queue *q)
+{
+	int ret = 0;
+
+	if (!q->dev)
+		return ret;
+
+	spin_lock_irq(q->queue_lock);
+	if (q->nr_pending) {
+		ret = -EBUSY;
+		pm_runtime_mark_last_busy(q->dev);
+	} else {
+		q->rpm_status = RPM_SUSPENDING;
+	}
+	spin_unlock_irq(q->queue_lock);
+	return ret;
+}
+EXPORT_SYMBOL(blk_pre_runtime_suspend);
+
+/**
+ * blk_post_runtime_suspend - Post runtime suspend processing
+ * @q: the queue of the device
+ * @err: return value of the device's runtime_suspend function
+ *
+ * Description:
+ *    Update the queue's runtime status according to the return value of the
+ *    device's runtime suspend function and mark last busy for the device so
+ *    that PM core will try to auto suspend the device at a later time.
+ *
+ *    This function should be called near the end of the device's
+ *    runtime_suspend callback.
+ */
+void blk_post_runtime_suspend(struct request_queue *q, int err)
+{
+	if (!q->dev)
+		return;
+
+	spin_lock_irq(q->queue_lock);
+	if (!err) {
+		q->rpm_status = RPM_SUSPENDED;
+	} else {
+		q->rpm_status = RPM_ACTIVE;
+		pm_runtime_mark_last_busy(q->dev);
+	}
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_post_runtime_suspend);
+
+/**
+ * blk_pre_runtime_resume - Pre runtime resume processing
+ * @q: the queue of the device
+ *
+ * Description:
+ *    Update the queue's runtime status to RESUMING in preparation for the
+ *    runtime resume of the device.
+ *
+ *    This function should be called near the start of the device's
+ *    runtime_resume callback.
+ */
+void blk_pre_runtime_resume(struct request_queue *q)
+{
+	if (!q->dev)
+		return;
+
+	spin_lock_irq(q->queue_lock);
+	q->rpm_status = RPM_RESUMING;
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_pre_runtime_resume);
+
+/**
+ * blk_post_runtime_resume - Post runtime resume processing
+ * @q: the queue of the device
+ * @err: return value of the device's runtime_resume function
+ *
+ * Description:
+ *    Update the queue's runtime status according to the return value of the
+ *    device's runtime_resume function. If it is successfully resumed, process
+ *    the requests that are queued into the device's queue when it is resuming
+ *    and then mark last busy and initiate autosuspend for it.
+ *
+ *    This function should be called near the end of the device's
+ *    runtime_resume callback.
+ */
+void blk_post_runtime_resume(struct request_queue *q, int err)
+{
+	if (!q->dev)
+		return;
+
+	spin_lock_irq(q->queue_lock);
+	if (!err) {
+		q->rpm_status = RPM_ACTIVE;
+		__blk_run_queue(q);
+		pm_runtime_mark_last_busy(q->dev);
+		pm_request_autosuspend(q->dev);
+	} else {
+		q->rpm_status = RPM_SUSPENDED;
+	}
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_post_runtime_resume);
+
+/**
+ * blk_set_runtime_active - Force runtime status of the queue to be active
+ * @q: the queue of the device
+ *
+ * If the device is left runtime suspended during system suspend the resume
+ * hook typically resumes the device and corrects runtime status
+ * accordingly. However, that does not affect the queue runtime PM status
+ * which is still "suspended". This prevents processing requests from the
+ * queue.
+ *
+ * This function can be used in driver's resume hook to correct queue
+ * runtime PM status and re-enable peeking requests from the queue. It
+ * should be called before first request is added to the queue.
+ */
+void blk_set_runtime_active(struct request_queue *q)
+{
+	spin_lock_irq(q->queue_lock);
+	q->rpm_status = RPM_ACTIVE;
+	pm_runtime_mark_last_busy(q->dev);
+	pm_request_autosuspend(q->dev);
+	spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_set_runtime_active);

block/blk-pm.h

@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _BLOCK_BLK_PM_H_
+#define _BLOCK_BLK_PM_H_
+
+#include <linux/pm_runtime.h>
+
+#ifdef CONFIG_PM
+static inline void blk_pm_requeue_request(struct request *rq)
+{
+	if (rq->q->dev && !(rq->rq_flags & RQF_PM))
+		rq->q->nr_pending--;
+}
+
+static inline void blk_pm_add_request(struct request_queue *q,
+				      struct request *rq)
+{
+	if (q->dev && !(rq->rq_flags & RQF_PM) && q->nr_pending++ == 0 &&
+	    (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING))
+		pm_request_resume(q->dev);
+}
+
+static inline void blk_pm_put_request(struct request *rq)
+{
+	if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending)
+		pm_runtime_mark_last_busy(rq->q->dev);
+}
+#else
+static inline void blk_pm_requeue_request(struct request *rq)
+{
+}
+
+static inline void blk_pm_add_request(struct request_queue *q,
+				      struct request *rq)
+{
+}
+
+static inline void blk_pm_put_request(struct request *rq)
+{
+}
+#endif
+
+#endif /* _BLOCK_BLK_PM_H_ */

block/elevator.c

@@ -41,6 +41,7 @@
 
 #include "blk.h"
 #include "blk-mq-sched.h"
+#include "blk-pm.h"
 #include "blk-wbt.h"
 
 static DEFINE_SPINLOCK(elv_list_lock);
@@ -557,27 +558,6 @@ void elv_bio_merged(struct request_queue *q, struct request *rq,
 		e->type->ops.sq.elevator_bio_merged_fn(q, rq, bio);
 }
 
-#ifdef CONFIG_PM
-static void blk_pm_requeue_request(struct request *rq)
-{
-	if (rq->q->dev && !(rq->rq_flags & RQF_PM))
-		rq->q->nr_pending--;
-}
-
-static void blk_pm_add_request(struct request_queue *q, struct request *rq)
-{
-	if (q->dev && !(rq->rq_flags & RQF_PM) && q->nr_pending++ == 0 &&
-	    (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING))
-		pm_request_resume(q->dev);
-}
-#else
-static inline void blk_pm_requeue_request(struct request *rq) {}
-static inline void blk_pm_add_request(struct request_queue *q,
-				      struct request *rq)
-{
-}
-#endif
-
 void elv_requeue_request(struct request_queue *q, struct request *rq)
 {
 	/*

drivers/scsi/scsi_pm.c

@@ -8,6 +8,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/export.h>
 #include <linux/async.h>
+#include <linux/blk-pm.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>

drivers/scsi/sd.c

@@ -45,6 +45,7 @@
 #include <linux/init.h>
 #include <linux/blkdev.h>
 #include <linux/blkpg.h>
+#include <linux/blk-pm.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
 #include <linux/string_helpers.h>

drivers/scsi/sr.c

@@ -43,6 +43,7 @@
 #include <linux/interrupt.h>
 #include <linux/init.h>
 #include <linux/blkdev.h>
+#include <linux/blk-pm.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/pm_runtime.h>

include/linux/blk-pm.h

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _BLK_PM_H_
+#define _BLK_PM_H_
+
+struct device;
+struct request_queue;
+
+/*
+ * block layer runtime pm functions
+ */
+#ifdef CONFIG_PM
+extern void blk_pm_runtime_init(struct request_queue *q, struct device *dev);
+extern int blk_pre_runtime_suspend(struct request_queue *q);
+extern void blk_post_runtime_suspend(struct request_queue *q, int err);
+extern void blk_pre_runtime_resume(struct request_queue *q);
+extern void blk_post_runtime_resume(struct request_queue *q, int err);
+extern void blk_set_runtime_active(struct request_queue *q);
+#else
+static inline void blk_pm_runtime_init(struct request_queue *q,
+				       struct device *dev) {}
+#endif
+
+#endif /* _BLK_PM_H_ */

include/linux/blkdev.h

@@ -1280,29 +1280,6 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id,
 extern void blk_put_queue(struct request_queue *);
 extern void blk_set_queue_dying(struct request_queue *);
 
-/*
- * block layer runtime pm functions
- */
-#ifdef CONFIG_PM
-extern void blk_pm_runtime_init(struct request_queue *q, struct device *dev);
-extern int blk_pre_runtime_suspend(struct request_queue *q);
-extern void blk_post_runtime_suspend(struct request_queue *q, int err);
-extern void blk_pre_runtime_resume(struct request_queue *q);
-extern void blk_post_runtime_resume(struct request_queue *q, int err);
-extern void blk_set_runtime_active(struct request_queue *q);
-#else
-static inline void blk_pm_runtime_init(struct request_queue *q,
-	struct device *dev) {}
-static inline int blk_pre_runtime_suspend(struct request_queue *q)
-{
-	return -ENOSYS;
-}
-static inline void blk_post_runtime_suspend(struct request_queue *q, int err) {}
-static inline void blk_pre_runtime_resume(struct request_queue *q) {}
-static inline void blk_post_runtime_resume(struct request_queue *q, int err) {}
-static inline void blk_set_runtime_active(struct request_queue *q) {}
-#endif
-
 /*
  * blk_plug permits building a queue of related requests by holding the I/O
  * fragments for a short period. This allows merging of sequential requests